The present invention relates to an apparatus and method for determining a position on a surface containing a coding pattern.
In many situations it is desirable to determine an absolute position on a surface. For example, it may be desirable to determine a position on a surface when recording and digitizing a document such as a drawing or map. It may also be desirable to determine a position of a surface when creating an electronic version of handwritten information.
In these and other situations where position-determination is carried out, it is often desirable to have a computer program, in cooperation with an input device, carry out position-determination calculation and, in particular, to read and process position information and other information that, for example, can be related to the absolute positions read and determined.
U.S. Pat. No. 5,852,434 describes a device for determining an absolute position. The device comprises a writing surface, which has a position-coding pattern for determining X-Y coordinates, a detector, which can detect the position-coding pattern, and a processor, which can determine the position of the detector in relation to the writing surface based on the detected position-coding pattern. The device allows a user to input handwritten or hand-drawn information to a computer at the same time the information is written or drawn on the writing surface.
Generally, the smaller the symbols are, the more difficult it is to produce the patterned writing surface and the greater the risk of incorrect position determinations. On the other hand, the larger the symbols are, the worse the position resolution.
In accordance with the invention, there may be provided a surface comprising a first coding pattern of symbols and a second coding pattern of symbols wherein each symbol of the first coding pattern has at least two different values and each symbol of the second coding pattern has at least two different values. Each symbol of the first coding pattern may be defined by a first raster point and at least one first marking, wherein the first raster point is included in a first raster, which extends over the surface. Each symbol of the second coding pattern may be defined by a second raster point and at least one second marking, wherein the second raster point is included in a second raster which is displaced in relation to the first raster and has a different spatial scale than the first raster.
There may also be provided, a device for reading a position-coding pattern and an information-coding pattern on a surface, wherein the position-coding pattern and the information-coding pattern include symbols which each represent at least two different values, wherein the values depend on position information and other information for the position-coding pattern and the information-coding pattern, respectively. The device may include means for reading a part of the surface and storing the information read in an image, means for determining a first virtual raster with first raster points in the image associated with the position-coding pattern and a second virtual raster with second raster points in the image associated with the information-coding pattern. The second raster may be displaced in relation to the first raster and may have spatial scale other than that of the first raster. The device may also include means for locating a plurality of symbols in the position-coding pattern and the information-coding pattern and means for determining the value of each of said plurality of symbols. Each symbol in the position-coding pattern a first raster point in the first raster and at least one first marking and each symbol in the information-coding pattern may include a second raster point in the second raster and at least one second marking. Further, the device may include means for separating the position-coding pattern in the image into a first position code for a first coordinate for the partial surface and a second position code for a second coordinate for the partial surface by translating the value of each symbol into at least one first digit for the first position code and at least a second digit for the second position code. Still further, the device may include means for calculating the first coordinate based on the first position code and the second coordinate based on the second position code.
Further, there may also be provided a method for producing a position-coding pattern and an information-coding pattern on a surface, wherein the coding patterns comprise symbols, which each represents at least two different values. The values may depend on position information and other information for the position-coding pattern and the information-coding pattern, respectively. The method may also include determining a first raster with first raster points and a second raster with second raster points. The second raster may be displaced in relation to the first raster and may have a different spatial scale than the first raster. The method may also include determining a configuration of the symbols of the position-coding pattern and the information-coding pattern. Each symbol of the position-coding pattern may be defined by a first raster point in the first raster and at least one first marking and each symbol in the second coding pattern may be defined by a second raster point in the second raster and at least one second marking.
The foregoing summarizes only a few aspects of the invention and is not intended to be reflective of the full scope of the invention as claimed. Additional features and advantages of the invention are set forth in the following description, may be apparent from the description, or may be learned by practicing the invention. Moreover, both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.